Recently, a composite of a silver particle and an organic compound is attracting attention as a material for forming electrodes, circuit patterns, etc. of electronic devices. In Patent Document 1, silver particles with an average particle diameter of 20 nm or less that have on their surfaces an organic compound having an unsaturated bond in its molecule, more specifically, oleylamine, are described as an ink material for an ink-jet printing method. In Patent Document 2, a silver colloidal solution containing silver-based particles prepared by providing a coating layer of polyvinylpyrrolidone, polyallylamine, or polyethyleneimine on the surfaces of silver particles having an average particle diameter of 10 nm or less is described as an ink material for an ink-jet printing method.